The present invention relates to a convenient-type miniature linear guide. More particularly, the present invention relates to a miniature linear guide of a type that is lubricated with a lubricant-containing polymer and which enables the lubricant to be supplied automatically for a prolonged period to a number of balls that rotate in a circulatory mode along grooves in a slider and that are components of the miniature linear guide.
An example of a conventional miniature linear guide is shown in FIGS. 5 and 6. The basic components of the miniature linear guide are an axially extending guide rail 1 substantially U-shaped in cross section and a slider 2 which is fitted in the guide rail 1 so that it is capable of sliding along the guide rail. The slider 2 is an integral assembly of a slider body 3, a circulator 4, and a holding plate 5. The slider body 3 is formed by pressing a plate material into a substantially U-shape in section. The circulator 4 is made by molding plastics in such a shape that it includes a ball circulating path formed therein. The circulator 4 and the holding plate 5 are fitted in a concave portion of the slider body 3, with the holding plate 5 being held between the slider body 3 and the circulator 4.
The inner surfaces of two side walls of the guide rail 1 are provided with axial loaded ball rolling grooves 1B whereas the outer surfaces of the respective side walls of the slider body 3 are provided with axial loaded ball rolling grooves 3B which are confronted with the grooves 1B. A number of balls 6 are incorporated in the grooves 1B and 3B, as well as in the ball circulating path in the circulator 4. The miniature linear guide shown in FIGS. 5 and 6 is so adapted that when the slider 2 is linearly moved along the guide rail 1, the balls 6 rollingly rotate in an endless circulating manner. The inside of the slider 2 is filled with a lubricant such as grease or lube oil for lubricating the rolling balls 6.
To insure that the balls move smoothly for an extended time, periodic refilling of the lubricant is necessary. However, with the miniature linear guide which is small in size and which hence requires a compact design, it is difficult to provide a lubricant refill port (e.g., a grease nipple) which is normally used with the standard linear guide. This has caused the disadvantage that periodic refilling of the lubricant is impossible without disassembling the miniature linear guide.
Another problem with the conventional miniature linear guide is that its small size prevents the provision of a completely sealed design and that, therefore, even if the miniature linear guide is filled with a lubricant to full capacity, the lubricant splashes outside the miniature linear guide during operation and cannot be retained for an intended long period, whereby the life of the miniature linear guide ends prematurely.
The conventional miniature linear guide has another problem in that a lubricant reservoir cannot be provided within the miniature linear guide, without blocking the circulation of balls because the size of the miniature linear guide is too small.